ARC on Objects not Class Definitions

[IbanezDavy via Digitalmars-d]

I actually asked this on reddit but I figured I'd pose the 
question here because it seems like a more fitting place for the 
discussion. I'd actually very much like to see ARC as an 
alternative to GC in D. I'd literally have no more excuses to use 
C++ anymore if that was the case. But after reading DIP74, I 
can't help but think the same mistake is being repeated with ARC 
that was repeated with the GC.

Usually how you allocate the object has very little to do with 
implementation of the object itself. So why have the @safe 
property specified when defining the class? Why not have it as a 
type qualifier for the object instead? This would allow people to 
opt in and out of both GC and ARC where they feel fit and not 
force some arbitrary allocation scheme that could function just 
as well with GC as with ARC. Furthermore, taking this idea to the 
logical extreme (this part isn't necessarily required), you could 
have another qualifier to allow you to manage the reference 
type's memory yourself. Something like @nogc or @unsafe would 
seem appropriate.

I figured I'd ask because it seemed to make a lot sense to me. 
Maybe one of you could enlighten me why this wouldn't work in D's 
case?